Several treatments genuinely slow hair loss and promote regrowth, ranging from over-the-counter topicals to prescription medications, nutritional fixes, and in-office procedures. What works best depends on the cause: pattern hair loss driven by hormones responds to different interventions than thinning caused by a nutrient deficiency or stress. Here’s what the evidence actually supports.
Why Hair Falls Out in the First Place
The most common cause of hair loss is androgenetic alopecia, or pattern hair loss, which affects both men and women. It’s driven by a hormone called DHT, a byproduct of testosterone that gradually shrinks hair follicles until they stop producing visible hair. In men this typically shows up as a receding hairline and thinning crown; in women it tends to cause diffuse thinning along the part line.
Other causes include telogen effluvium, a temporary shedding triggered by stress, illness, crash dieting, or hormonal shifts like postpartum changes. Nutritional deficiencies, thyroid disorders, autoimmune conditions, and certain medications can also trigger hair loss. Identifying the underlying cause matters because it determines which treatments will help.
Medications With the Strongest Evidence
Two drugs remain the gold standard for pattern hair loss: minoxidil and finasteride. They work through completely different mechanisms, and combining them tends to outperform either one alone.
Minoxidil is available over the counter as a topical liquid or foam (typically 2% or 5% strength). It increases blood flow to hair follicles and extends the growth phase of the hair cycle. Peak regrowth with topical minoxidil occurs after about one year of consistent daily use, though measurable improvements show up between months four and six. A low-dose oral form is increasingly prescribed for people who find the topical version irritating or inconvenient to apply.
Finasteride is a prescription pill that blocks roughly 70% of DHT production, directly targeting the hormone responsible for follicle miniaturization. In two large one-year trials involving over 1,500 men, 99% of those taking finasteride showed either decreased progression or actual reversal of hair loss. The main concern is sexual side effects. In clinical trials, 15% of finasteride users reported drug-related sexual side effects during the first year, compared to 7% on placebo. By years two through four, new sexual side effects occurred at the same 7% rate in both groups, suggesting most issues emerge early. Only 4% of finasteride users discontinued due to these effects, and about half of those saw resolution after stopping the medication.
When the two drugs are combined at low oral doses, results improve further. A 12-month evaluation of over 500 men found that 92% were stable or improved, with 57% showing overt regrowth.
Nutritional Deficiencies That Cause Thinning
If your hair loss stems from a nutritional gap rather than hormones, no amount of minoxidil will fix it until the deficiency is corrected. The nutrients most strongly linked to hair loss are iron, zinc, and vitamin D.
Iron deficiency is one of the most common correctable causes of hair shedding, particularly in women. Dermatologists generally aim for ferritin levels above 50 to 70 micrograms per liter for hair health, which is higher than the threshold used to diagnose anemia. You can be losing hair from low iron stores without technically being anemic. If iron supplementation alone doesn’t raise your levels, adding the amino acid L-lysine (found in meat, eggs, and legumes) has been shown to significantly boost ferritin absorption in women with chronic shedding who hadn’t responded to iron alone.
Zinc plays a role in hair follicle function, and studies have found that people with various types of hair loss consistently have lower zinc levels than healthy controls. The tricky part is that functional zinc deficiency can affect hair before blood levels drop below the standard “normal” range, making it easy to miss on routine labs.
The Truth About Biotin Supplements
Biotin is the most heavily marketed hair supplement, but the evidence behind it is thin. A review published in Skin Appendage Disorders concluded there is no evidence that biotin supplementation benefits people who aren’t actually deficient. No randomized controlled trials have shown it helps healthy individuals with normal biotin levels, and lab studies found that biotin doesn’t influence the growth or development of normal hair follicle cells.
True biotin deficiency is uncommon in people eating a balanced diet. It’s most often seen in people who consume large amounts of raw eggs, take certain anticonvulsant medications, are pregnant, have alcohol use disorder, or have a rare genetic condition. If you do have a genuine deficiency (defined as levels below 200 nanograms per liter), supplementation can reverse hair loss. But for the average person buying biotin gummies at the drugstore, the benefit is likely negligible.
Rosemary Oil as a Natural Alternative
For those looking for a non-pharmaceutical option, rosemary oil has the most credible clinical data of any botanical treatment. A randomized trial compared rosemary oil head-to-head with 2% minoxidil in 100 people with pattern hair loss over six months. Both groups saw a significant increase in hair count by the six-month mark, with no statistical difference between them. Neither group showed meaningful change at three months, reinforcing that patience is essential with any hair treatment.
Rosemary oil did have one advantage: less scalp itching than minoxidil. It’s worth noting that this study compared rosemary oil to the lower 2% concentration of minoxidil, not the stronger 5% version. Still, the results suggest rosemary oil is a reasonable option, particularly for people with mild thinning or those who want to avoid pharmaceutical treatments.
In-Office Procedures
Platelet-rich plasma (PRP) therapy involves drawing your blood, concentrating the growth-factor-rich plasma, and injecting it into the scalp. In a randomized placebo-controlled trial, patients who received three PRP sessions spaced 30 days apart saw a mean increase of about 46 hairs per square centimeter compared to baseline, while the untreated control areas actually lost a small amount of density. Results typically become visible after the third session, with maintenance treatments recommended every several months.
Hair transplant surgery relocates follicles from the back and sides of the scalp (which are resistant to DHT) to thinning areas. At one year post-surgery, about 81% of patients in one study showed good results. However, long-term follow-up tells a more nuanced story: by four years, only about 9% of patients retained their original transplanted density unchanged, while the majority experienced some degree of density reduction. This highlights an important point: transplants redistribute existing hair, but they don’t stop the underlying process causing loss. Most surgeons recommend continuing medication after a transplant to protect both the transplanted and native hair.
How Long Before You See Results
Hair grows slowly, and treatments work on the hair cycle rather than producing overnight change. Nearly every effective intervention requires three to six months of consistent use before visible improvement appears. With topical minoxidil, significant differences from baseline typically show up around months four to six, with peak results at one year. Finasteride follows a similar timeline. Marine protein-based supplements and other nutraceuticals that have shown benefit in clinical trials generally need at least 90 days.
One counterintuitive thing to expect: many treatments cause a temporary increase in shedding during the first few weeks. This happens because the treatment pushes resting follicles into a new growth cycle, which means the old hair falls out to make way for new growth. It’s a sign the treatment is working, not failing. If you quit during this phase, you lose the benefit without ever seeing the payoff.
Matching Treatment to the Cause
Pattern hair loss responds best to DHT-blocking medication (finasteride or its natural, less potent alternative, saw palmetto) combined with a growth stimulator like minoxidil or rosemary oil. Nutritional hair loss requires identifying and correcting the specific deficiency. Stress-related shedding (telogen effluvium) is usually self-limiting and resolves within six to twelve months once the trigger passes, though some people use minoxidil to speed recovery.
The single most important factor in treating hair loss is starting early. Treatments are far better at maintaining existing hair than regrowing what’s already gone. A follicle that has been miniaturized for years is much harder to revive than one that recently started shrinking. If you’ve noticed your part widening or your hairline creeping back, the sooner you act, the more hair you’ll keep.